Pre-heat oven to 350ºF (180ºC).
Grease with butter an 8 x 8 inch (20 x 20 cm) baking dish.
Break the bread into 2 inch (5 cm) cubes and place them in the baking dish. Then drizzle with the melted butter and sprinkle with the raisins. Set it aside.
Beat the eggs in a medium bowl, add the brown sugar, white sugar, vanilla extract, cinnamon, nutmeg and salt and mix well. Add the milk and whisk again. Pour the custard over the pieces of bread and let it stand for about 30-60 minutes (the longer, the better) so it can absorb the custard well.
Bake for 45-55 minutes or until a toothpick inserted in the middle comes out clean. If you notice that the top is starting to get dark, you can loosely cover it with aluminum foil.
Take the bread pudding out of the oven and let it cool for at least 10 minutes before serving.